- Haskell-Cafe - Haskell.org

Applicative Monoid instance
by Brian Hurt 06 Sep '16

06 Sep '16

This may be a stupid question, but I'm wondering why the following instance isn't in prelude: instance (Applicative m, Monoid a) => Monoid (m a) where mempty = pure mempty mappend a b = mappend <$> a <*> b ? I ask, because being able to use a WriterT (IO ()) STM a to debug complex STM expressions would be really nice. But it depends upon IO () being a monoid. Brian

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[ANN] Microspec
by amindfv＠gmail.com 06 Sep '16

06 Sep '16

Happy to announce the release of a new, tiny property-based test framework: Microspec. Microspec has a clean RSpec/HSpec-style API, depends only on base and QuickCheck, runs unit and property-based tests, and is well under 500 lines of code. If you'd like to add tests to your code but don't like increasing the amount of code you depend on, give Microspec a try: https://hackage.haskell.org/package/microspec Happy hacking! Tom

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[ANN] Darcs 2.12.1 release
by Guillaume Hoffmann 06 Sep '16

06 Sep '16

Hi all, The Darcs team is pleased to announce the release of Darcs 2.12.1. The most important changes are: * fixes for building with GHC 8 * drop support for GHC 7.6 and 7.8, i.e., require GHC 7.10 * improvements in `darcs whatsnew` output with irrelevant files (Ben Franksen) This release can be installed via cabal or (soon) stack. The 2.12 branch is also available as a darcs repository from http://darcs.net/releases/branch-2.12 . Thanks! Guillaume Hoffmann

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PEPM 2017 Final Call for Papers (submission deadline extension: 30th Sep.)
by Jeremy Yallop 04 Sep '16

04 Sep '16

FINAL CALL FOR PAPERS Workshop on PARTIAL EVALUATION AND PROGRAM MANIPULATION (PEPM 2017) NEWS: Deadline extension to 30th September (see below) NEWS: Keynote talk by Neil Jones, DIKU (see below). http://conf.researchr.org/home/PEPM-2017 Paris, France, January 16th - 17th, 2017 (co-located with POPL 2017) PEPM is the premier forum for discussion of semantics-based program manipulation. The first ACM SIGPLAN PEPM symposium took place in 1991, and meetings have been held in affiliation with POPL every year since 2006. PEPM 2017 will be based on a broad interpretation of semantics-based program manipulation, reflecting the expanded scope of PEPM in recent years beyond the traditionally covered areas of partial evaluation and specialization. Specifically, PEPM 2017 will include practical applications of program transformations such as refactoring tools, and practical implementation techniques such as rule-based transformation systems. In addition, the scope of PEPM covers manipulation and transformations of program and system representations such as structural and semantic models that occur in the context of model-driven development. In order to maintain the dynamic and interactive nature of PEPM and to encourage participation by practitioners, we also solicit submissions of short papers, including tool demonstrations, and of posters. Scope ----- Topics of interest for PEPM 2017 include, but are not limited to: * Program and model manipulation techniques such as: supercompilation, partial evaluation, fusion, on-the-fly program adaptation, active libraries, program inversion, slicing, symbolic execution, refactoring, decompilation, and obfuscation. * Program analysis techniques that are used to drive program/model manipulation such as: abstract interpretation, termination checking, binding-time analysis, constraint solving, type systems, automated testing and test case generation. * Techniques that treat programs/models as data objects including metaprogramming, generative programming, embedded domain-specific languages, program synthesis by sketching and inductive programming, staged computation, and model-driven program generation and transformation. * Application of the above techniques including case studies of program manipulation in real-world (industrial, open-source) projects and software development processes, descriptions of robust tools capable of effectively handling realistic applications, benchmarking. Examples of application domains include legacy program understanding and transformation, DSL implementations, visual languages and end-user programming, scientific computing, middleware frameworks and infrastructure needed for distributed and web-based applications, embedded and resource-limited computation, and security. This list of categories is not exhaustive, and we encourage submissions describing applications of semantics-based program manipulation techniques in new domains. If you have a question as to whether a potential submission is within the scope of the workshop, please contact the programme chairs. Submission categories and guidelines ------------------------------------ Three kinds of submissions will be accepted: Regular Research Papers, Short Papers and Posters. * Regular Research Papers should describe new results, and will be judged on originality, correctness, significance and clarity. Regular research papers must not exceed 12 pages in ACM Proceedings style (including appendix). * Short Papers may include tool demonstrations and presentations of exciting if not fully polished research, and of interesting academic, industrial and open-source applications that are new or unfamiliar. Short papers must not exceed 6 pages in ACM Proceedings style (including appendix). * Posters should describe work relevant to the PEPM community, and must not exceed 2 pages in ACM Proceedings style. We invite poster submissions that present early work not yet ready for submission to a conference or journal, identify new research problems, showcase tools and technologies developed by the author(s), or describe student research projects. At least one author of each accepted contribution must attend the workshop and present the work. In the case of tool demonstration papers, a live demonstration of the described tool is expected. Suggested topics, evaluation criteria, and writing guidelines for both research tool demonstration papers will be made available on the PEPM 2017 web site. Student participants with accepted papers can apply for a SIGPLAN PAC grant to help cover travel expenses and other support. PAC also offers other support, such as for child-care expenses during the meeting or for travel costs for companions of SIGPLAN members with physical disabilities, as well as for travel from locations outside of North America and Europe. For details on the PAC programme, see its web page. Publication and special issue ----------------------------- All accepted papers, short papers and posters included, will appear in formal proceedings published by ACM Press. Accepted papers will be included in the ACM Digital Library. Authors of selected papers from PEPM 2016 and PEPM 2017 will also be invited to expand their papers for publication in a special issue of the journal Computer Languages, Systems and Structures (COMLAN, Elsevier). Keynote ------- Neil Jones (DIKU) will give the PEPM keynote talk, titled Compiling Untyped Lambda Calculus to Lower-level Code by Game Semantics and Partial Evaluation Best paper award ---------------- PEPM 2017 continues the tradition of a Best Paper award. The winner will be announced at the workshop. Submission ---------- Papers should be submitted electronically via HotCRP. https://pepm17.hotcrp.com/ Authors using LaTeX to prepare their submissions should use the new improved SIGPLAN proceedings style, and specifically the sigplanconf.cls 9pt template. Important Dates --------------- UPDATE: following feedback from potential authors, we have extended the PEPM submission dates by two weeks to avoid clashes with other events. The new deadlines are consequently strict, and there will be no further extensions. For Regular Research Papers and Short Papers: * Abstract submission : Tuesday 27th September 2016 * Paper submission : Friday 30th September 2016 * Author notification : Friday 4th November 2016 * Camera ready : Monday 28th November 2016 For Posters: * Poster submission : Tuesday 8th November 2016 * Author notification : Friday 18th November 2016 * Camera ready : Monday 28th November 2016 PEPM workshop: * Workshop : Monday 16th - Tuesday 17th January 2017 The proceedings will be published 2 weeks pre-conference. AUTHORS TAKE NOTE: The official publication date is the date the proceedings are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of your conference. The official publication date affects the deadline for any patent filings related to published work. (For those rare conferences whose proceedings are published in the ACM Digital Library after the conference is over, the official publication date remains the first day of the conference.). PEPM'17 Programme Committee --------------------------- Elvira Albert (Complutense University of Madrid, Spain) Don Batory (University of Texas at Austin, USA) Martin Berger (University of Sussex, UK) Sebastian Erdweg (TU Delft, Netherlands) Andrew Farmer (Facebook, USA) Matthew Flatt (University of Utah, USA) John Gallagher (Roskilde University, Denmark) Robert Glück (DIKU, Denmark) Jurriaan Hage (Utrecht University, Netherlands) Zhenjiang Hu (National Institute of Informatics, Japan) Yukiyoshi Kameyama (University of Tsukuba, Japan) Ilya Klyuchnikov (Facebook, UK) Huiqing Li (EE, UK) Annie Liu (Stony Brook University, USA) Markus Püschel (ETH Zurich, Switzerland) Ryosuke SATO (University of Tokyo, Japan) Sven-Bodo Scholz (Heriot-Watt University, UK) Ulrik Schultz (co-chair) (University of Southern Denmark) Ilya Sergey (University College London, UK) Chung-chieh Shan (Indiana University, USA) Tijs van der Storm (Centrum Wiskunde & Informatica, Netherlands) Jeremy Yallop (co-chair) (University of Cambridge, UK)

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Data.Conduit.Binary question
by Michael Litchard 04 Sep '16

04 Sep '16

I'd like to use conduits to (1) read a binary file in chunks (2) take an md5 of that chunk (3) write the chunk to a file (4) write md5 to file. I'm looking at Data.Conduit.Binary. Do I want sourceFileRange for (1)?

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Travis/Cabal help
by David Feuer 03 Sep '16

03 Sep '16

Gabriel Gonzalez has gotten Cabal benchmark integration working for containers, and then I broke it without realizing I'd done so because Travis CI wasn't building the benchmarks. When I got them working again locally and tried enabling them in .travis.yml (just adding --enable-benchmarks to the cabal configure line), things went kablooey: https://travis-ci.org/haskell/containers/jobs/156997144 Does anyone know how to interpret those entrails? Is this something that can be fixed?

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[ANN] lentil - frugal issue tracker
by Francesco Ariis 02 Sep '16

02 Sep '16

I am pleased to announce the release of lentil 1.0 [0]. [0] http://hackage.haskell.org/package/lentil-1.0.0.1 ============================= lentil - frugal issue tracker ============================= lentil is a minimum effort issue tracker; if you litter your code with: -- FIXME: does outPop work with b/w terminals? [ansi] lentil can help you listing, sorting, exporting, tagging slicing and dicing those `todo`s. To see it in action just type: cabal install lentil # or use stack cd ~/your-project-folder/ lentil . Any repo will do, not only Haskell ones! For further information, check the project homepage [1] and the user manual [2]. [1] http://ariis.it/static/articles/lentil/page.html [2] http://ariis.it/static/articles/lentil-manual/page.html Heartfelt "thank you!" to anyone who contributed [3] by providing valuable feedback, suggestions, patches! [3] http://ariis.it/link/repos/lentil/contributors.txt

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StdGen Reliability Across Versions / Systems
by Christopher Howard 02 Sep '16

02 Sep '16

I know that, ff you feed mkStdGen a particular seed, and pull a list of random numbers from that StdGen, that that the list will always be the same if your run your compiled program over and over again on that same system. But which of the following will cause you to get different output?: 1) Changes in GHC version 2) Changes in "random" library version 3) Compiling / Running on a different host computer (but compiling with the same GHC & random versions. -- https://qlfiles.net My PGP public key ID is 0x340EA95A (pgp.mit.edu)

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new edition of "Programming in Haskell"
by Gregory Guthrie 01 Sep '16

01 Sep '16

>> I'm delighted to announce that the new edition of "Programming in >> Haskell" is now available! Further details are provided below, >> and are also available from: http://tinyurl.com/hnfjdgc. This is great, and a welcome update, thank you! +1 for book and update :-) -1 for DRM on eBook :-( -------------------------------------------

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New edition of "Programming in Haskell"
by Graham Hutton 01 Sep '16

01 Sep '16

Dear all, I'm delighted to announce that the new edition of "Programming in Haskell" is now available! Further details are provided below, and are also available from: http://tinyurl.com/hnfjdgc. Best wishes, Graham ================================================================= *** BOOK ANNOUNCEMENT *** Programming in Haskell - 2nd Edition Graham Hutton, University of Nottingham Cambridge University Press, 1st September 2016 320 pages, 120 exercises, ISBN 9781316626221 http://tinyurl.com/hnfjdgc ================================================================= DESCRIPTION: Haskell is a purely functional language that allows programmers to rapidly develop clear, concise, and correct software. The language has grown in popularity in recent years, both in teaching and in industry. This book is based on the author's experience of teaching Haskell for more than twenty years. All concepts are explained from first principles and no programming experience is required, making this book accessible to a broad spectrum of readers. While Part I focuses on basic concepts, Part II introduces the reader to more advanced topics. This new edition has been extensively updated and expanded to include recent and more advanced features of Haskell, new examples and exercises, selected solutions, and freely downloadable lecture slides and example code. The presentation is clean and simple, while also being fully compliant with the latest version of the language, including recent changes concerning applicative, monadic, foldable, and traversable types. ================================================================= CONTENTS: Foreword Preface Part I. Basic Concepts: 1. Introduction 2. First steps 3. Types and classes 4. Defining functions 5. List comprehensions 6. Recursive functions 7. Higher-order functions 8. Declaring types and classes 9. The countdown problem Part II. Going Further: 10. Interactive programming 11. Unbeatable tic-tac-toe 12. Monads and more 13. Monadic parsing 14. Foldables and friends 15. Lazy evaluation 16. Reasoning about programs 17. Calculating compilers Appendix A. Selected solutions Appendix B. Standard prelude Bibliography Index ================================================================= AUTHOR: Graham Hutton is Professor of Computer Science at the University of Nottingham. He has taught Haskell to thousands of students and received numerous best lecturer awards. Hutton has served as an editor of the Journal of Functional Programming, Chair of the Haskell Symposium and the International Conference on Functional Programming, and Vice-Chair of the ACM Special Interest Group on Programming Languages, and he is an ACM Distinguished Scientist. ================================================================= This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system, you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.

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